The use of bottom-up approaches to semiconductor fabrication has grown in interest within the scientific community (for example see Thurn-Albrecht et al, Ultrahigh Nanowire Arrays Grown in Self-Assembled. Diblock Copolymer Templates, Science 290, 2126-2129, 2000 and Black et al. Integration of Self-Assembled Diblock Copolymers for Semiconductor Capacitor Fabrication, Applied Physics Letters, 79, 409-411, 2001). One such approach utilizes block copolymers for generating sub-optical ground rule patterns. In particular, one illustrative use involves forming a ‘honeycomb’ structure with a poly (methyl methacrylate-b-styrene) block copolymer. In the case of a cylindrical phase diblock having a minor component of PMMA, the PMMA block can phase separate to form vertically oriented cylinders within the matrix of the polystyrene block upon a thermal anneal (Thurn-Albrecht et al, supra and Black et al. supra).
This process is shown in FIGS. 1a-1c. A substrate PA2-100 is optionally coated with a random copolymer PA2-110. This copolymer is affixed to the surface and excess material is removed. A block copolymer. PA2-120 is, coated on the top surface of the random-substrate stack as shown in FIG. 1a. A key attribute of this approach is that the neutral surface energy underlayer copolymer be covalently bound to the substrate such that it is not removed during the application of the subsequent diblock layer. Further, this underlayer polymer is prepared so that it will form a polymeric brush, i.e., having a single reactive end group introduced by a special initiator. Also typical is the requirement that this underlayer polymer have relatively monodisperse molecular weight distribution. A requirement of the substrate is that it has the necessary reactivity for the end group of the polymeric brush to covalently bond to it. The block copolymer PA2-120 is annealed with heat and/or in the presence of solvents, which allows for phase separation of the immiscible polymer blocks PA2-121 and PA2-122 as shown in FIG. 1b. The annealed film is then developed by a suitable method such as immersion in a solvent/developer which dissolves one polymer block and not the other, and reveals a pattern PA2-123 that is commensurate with the positioning of one of the blocks in the copolymer. For simplicity, in FIG. 1c the block is shown as completely removed although this is not required.
Since block copolymers have a natural length scale associated with their molecular weight and composition, the morphology of a phase-separated block copolymer can be tuned to generate cylinders of a specific width and on a specific pitch. Literature shows the use of UV exposure to cause the polymethylmethacrylate (PMMA) component of a typical diblock copolymer to decompose into smaller molecules (see Thurn-Albrecht et al, supra) and, further, developed using glacial acetic acid to remove the small molecules. Others simply develop acetic acid to reveal the HCP (Hexagonal closed packed or hexagonal array of cylinders) pattern (Black et al. supra). A third possible development technique involves using an oxygen plasma, which preferentially etches, for example, PMMA at a higher rate than polystyrene, the other component of a typical diblock copolymer (see Akasawa et al., Nanopatterning with Microdomains of Block Copolymers for Semiconductor Capacitor Fabrication, Jpn. J. Appl. Phys. Vol 41, 2002, pp 6112-6118).
Recent literature demonstrates the self-aligned formation of diblock copolymers within lithographically defined regions on a substrate. This process is shown in FIGS. 2a-2e. In FIG. 2a, topography 3140 in a material 3130 is generated lithographically on a stack of materials 3120, 3110 on a substrate 3100. The materials tack 3120 and 3110 can represent a single material or a stack of materials individually. In FIG. 2b, a Diblock copolymer film 3150 is coated over the topography. In FIG. 2c, the film is annealed allowing for phase separation in two individual components 3151 and 3152. In principle, there may be two or more domains. In FIG. 2d, a single domain of the Diblock is developed revealing the pattern 3160. In principle, the pattern can be within the trough or on top of the trough 3140 (shown in FIG. 2a). The Diblock can be partially developed as well. The resulting pattern can then be transferred into the material stack to generation a pattern 3170 as shown in FIG. 2e. 
Thus, previous embodiments entail forming an underlayer of neutral surface energy [see Huang PhD Thesis, U. Mass, 1999] polymeric brushes of narrow polydispersity and limited reactivity requiring a suitably reactive underlayer. This requires a reactive end group on the polymer brush to be introduced via a specially prepared, initiator that was also typically utilized to control the molecular weight and polydispersity of the copolymer. This provides only a single reactive end group per chain with which to bind to a suitable reactive substrate, e.g., the silanol groups on a SiO2 substrate. This is a limitation of this process. Additionally the reactivity of this system is limited by the single reactive site of the end group requiring relatively long processing times. If the polymer brushes are not covalently bound to the substrate they would be removed during application of the subsequent diblock layer and formation of the aligned self-assembled domains would not occur or be hampered. To this is added synthetic complexity of preparing suitable initiators and unconventional polymerization techniques.